A belt drive for a roller conveyor consists of pressing rollers for pressing a drive belt against the conveyor rollers of the roller conveyor in which the conveyor rollers as well as the pressing rollers are arranged on a profiled part which laterally adjoins the roll conveyor and the drive belt travels between the pressing rollers and the conveyor rollers.
The conveyor rollers of a roller conveyor are customarily driven by a sprocket wheel which is arranged on the conveyor rollers and a driven chain guided over it. Such a drive of the conveyor rollers is, to be sure, reliable but it nevertheless has certain disadvantages. Thus, in particular, this type of drive by chain is very noisy and furthermore expensive, since each conveyor roller must have such a sprocket wheel. Furthermore, in a chain drive for the conveyor rollers the weight of the roller conveyor is considerably increased by the chain and the sprocket wheels. Furthermore, the chain and the sprocket wheels must be regularly serviced in order to assure disturbance-free operation of the roller conveyor.
In order to avoid these disadvantages it is known to drive the conveyor rollers of a roller conveyor by a drive belt. For this purpose, pressing rollers are arranged below the conveyor rollers and press the drive belt against the conveyor roller. As means of suspension for the conveyor rollers and the pressing rollers there is used here the frame of the conveyor roller which limits it on the side. The known arrangement with pressing rollers, the drive belt which preferably consist of polyurethane, and the corresponding conveyor rollers is substantially quieter than a chain drive. Furthermore, due to the elimination of the sprocket wheels the conveyor rollers can be more simply shaped, which substantially reduces the cost of manufacturing the roller conveyor. In this type of drive, the drive belt is developed as an endless belt and is driven by a motor.
The profiled parts of the frame of the roller conveyor are prefabricated and are already provided with holes for the suspension or mounting of the conveyor rollers and drive rollers. The tolerance problems with regard to the profiled parts which are unavoidable in manufacture and, in particular, the position of the holes however make expensive adjustment devices necessary in order to provide assurance that the drive belt is pressed sufficiently firmly by the pressing roller against the conveyor roller to assure the drive of the conveyor roller. Such adjustment devices can, for instance, be slots rather than holes for receiving the pressing rollers. By means of the slots it is then possible properly to adjust the individual pressing rollers so as to compensate for the manufacturing tolerances. Since the roller conveyor, however, has a large number of pressing rollers even in the case of a relatively short conveyance path, the adjustment of the individual pressing rollers is extremely time-consuming and thus expensive. This is not changed if, instead of the pressing roller or in addition to it, the conveyor rollers can also be adjusted by a corresponding formation of slots.